The Regency era of British history is commonly described as the years between c. 1795 and 1837, although the official regency for which it is named only spanned the years 1811 to 1820. King George III first suffered debilitating illness in the late 1780s, and relapsed into his final mental illness in 1810; by the Regency Act 1811, his eldest son George, Prince of Wales, was appointed prince regent to discharge royal functions. When George III died in 1820, the Prince Regent succeeded him as George IV. In terms of periodisation, the longer timespan is roughly the final third of the Georgian era (1714–1837), encompassing the last 25 years or so of George III's reign, including the official Regency, and the complete reigns of both George IV and his brother and successor William IV. It ends with the accession of Queen Victoria in June 1837 and is followed by the Victorian era (1837–1901).

The history of the British Isles began with its sporadic human habitation during the Palaeolithic from around 900,000 years ago. The British Isles has been continually occupied since the early Holocene, the current geological epoch, which started around 11,700 years ago. Mesolithic hunter-gatherers migrated from the Continent soon afterwards at a time when there was no sea barrier between Britain and Europe, but there was between Britain and Ireland. There were almost complete population replacements by migrations from the Continent at the start of the Neolithic around 4,100 BC and the Bronze Age around 2,500 BC. Later migrations contributed to the political and cultural fabric of the islands and the transition from tribal societies to feudal ones at different times in different regions.